1. Field of the Invention
The present invention relates to pressure sensors and, more particularly, to a pressure sensor wherein a detector element, which detects a pressure, and a terminal, through which the detector is connected to an external circuit, which is connected by wire bonding and wherein the detector element is sealed by a diaphragm by means of oil.
2. Description of the Related Art
In recent years, due to electronic equipments use of digital technology, serious issues have arisen from electromagnetic waves at various frequencies adversely affecting other electronic equipment.
More particularly, probabilities occur wherein electronic equipment is adversely affected with the magnetic waves radiated from other electronic equipment, resulting in failures such as degraded functions, erroneous operations and unintended shutdowns. This is because the electromagnetic waves, taken into electronic equipment, serve as noises that cause failures to occur in internal parts of electronic equipment.
A pressure sensor, adapted to be installation on a vehicle, forms one part of electronic equipment that is susceptible to adverse affects caused by the electromagnetic waves. In particular, the electromagnetic waves, radiated from electronic devices such as an ECU installed on the vehicle, transfer through wirings, to which the pressure sensor is connected, and enter the pressure sensor, causing failures. To address such issues, it is highly required for the pressure sensor to be protected from such noises.
As measures to address the noises described above, it is conceived that capacitors are electrically connected to terminals of the pressure sensor to allow noises, inputted through the terminals, to transfer to a ground terminal for thereby outputting the noises to an outside of the pressure sensor. Such measures are deemed to be advisable for the capacitors, placed on the terminals, to block the noises admitted through the wirings to prevent the noises from entering the pressure sensor.
Therefore, various research and development work has heretofore been undertaken by the present inventors to provide and study prototypes of a structure in which the capacitors are placed on the terminals in a manner described above. One of such exemplary structures includes a connector case, with capacitors placed on terminals, which is shown in FIGS. 6A to 6C.
FIGS. 6A to 6C are views for illustrating a method of manufacturing a connector case of a pressure sensor wherein the capacitors 16 are placed on a position between the terminals 12a and 12b and a position between the terminals 12b and 12c. 
As shown in FIGS. 6A and 6B, first, the terminals 12a to 12c are molded with resin to form a primary molded section 101 in a manner to hold the terminals 12a to 12c. More particularly, first, press forming is executed on a sheet of metal to form a terminal component 121 having three terminals 12 involving a power supply terminal 12a, a signal output terminal 12b and a ground terminal 12c. The terminal component 121, formed in such a structure, has bar portions through which the respective terminals 12a to 12c are integrally connected.
Then, a given area of the terminal component 121 is molded with resin, such as polyphenilene sulfide, to form the primary molded section 101 (in primary molding step). That is, the terminal component 121 is set in a molding die, to which melted resin is poured and hardened to form the primary molded section 101 of resin on the terminal component 121. Subsequently, the bar portions, through which the respective terminals 12 are connected, are cut out. This causes the terminals 12 to be electrically disconnected. Then, the capacitors (for instance, ceramic capacitors) 16 are connected to the associated terminals 12 by welding. More particularly, as shown in FIG. 6A, wirings 16a of the capacitors 16 are welded to and connected between the terminals 12a and 12b and between the terminals 12b and 12c. 
Next, the primary molded section 101 is molded with resin to form a secondary molded section 102 serving as a connector case 10. That is, as shown in FIG. 16C, the terminals 12, resulting from the primary molding step shown in FIGS. 6A and 6B, are set in a molding die of the connector case 10 and melted resin is poured into the molding die through resin pouring ports 103, shown in FIG. 6C, thereby forming a secondary molded section 102 (in secondary molding step) serving as the connector case 10. In such a manner, the connector case 10 in which the capacitors 16 are incorporated is completed.
Thus, connecting the capacitors to the associated terminals and forming the primary and secondary molded sections of resin enables the connector case 10, incorporating the capacitors 16, to be formed.
However, if the capacitors 16 are connected to the associated terminals 12, respectively, as shown in FIGS. 6A and 6B, melted resin is caused to rush into the molding die of the connector case 10 with a great force from the resin pouring ports 103 shown in FIG. 6C and, due to such rushing flow of resin, issues arise with a tendency wherein the capacitors 16 are dislocated from the associated terminals 12.
More particularly, with melted resin poured through the resin pouring ports 103 into the molding die, melted resin introduced from the resin pouring ports 103 passes across the capacitors 16 and flows in a direction toward distal ends of the terminals 12. Due to such flow of melted resin, the capacitors 16 suffer from stresses such that the capacitors 16 are forced toward the distal ends of the terminals 12. That is, the capacitors 16 are pulled and pushed down in a direction opposing to the flow of resin. When this takes place, the capacitors 16 are pushed in a direction toward the distal ends of the terminals 12 and lead wires 16a are twisted, causing welded portions of the lead wires 16a to be torn off from the associated terminals 12. This results in electrically disconnected conditions between the capacitors 16 and the terminals 12.
To address such issues, it is conceived that the lead wires 16a of the capacitors 16 are welded to the associated terminals 12 in an area near an interior of the pressure sensor, as viewed in FIGS. 6A and 6B, at positions of close proximity to the primary molded section 101 upon which the capacitors 16 are pulled down in a direction wherein resin flows. With such a measure, it is considered that no lead wires 16a of the capacitors 16 tend to be torn away from the associated terminals due to the stresses caused by the flow of resin and the capacitors 16 are deemed to resist the flow of melted resin during the formation of the secondary molded section 102. However, the presence of the primary molded section 101 with an increased height provides disturbances with the resultant difficulty in welding the lead wires 16a to the associated terminals at positions closer to the primary molded section 101. Thus, it becomes difficult for the lead wires 16a of the capacitors 16 to be welded to the associated terminals at positions closer to the primary molded section 101 near the interior of the pressure sensor.